The problem, in other words, is not that Hampton Creek Foods is offering an alternative to traditional mayonnaise but that it is marketing it as indiscernible from the conventional option.
"It's one thing to enjoy some of the halo for mayonnaise, but it's another to dupe consumers," said Parke Wilde, an associate professor at the Friedman School of Nutrition Science and Policy at Tufts University.
"I think they're probably a little over that line with 'Just Mayo'. I can definitely see how it's a bit misleading."
Hampton Creek's chief executive, Josh Tetrick, could not immediately be reached for comment. Tetrick, who has lined up big-name investors such as Microsoft founder Bill Gates and tech entrepreneur Peter Thiel, has long said the goal of the San Francisco-based start-up is to produce food that is both healthy and affordable.
Last year he defended his product's name and branding, insisting that the goal was to reach a broad audience.
"We built the company to try to really penetrate the places where better-for-you food hasn't gone before, and that means right in the condiment aisle of Wal-Mart," Tetrick told The Washington Post.
Hampton Creek has had success in that area, striking deals with a range of huge retailers, including Costco.
But the company's venture into the market for America's best-selling condiment, mayonnaise, has at times hit some snags.
Last year, food giant Unilever, maker of popular Hellmann's mayo, sued Hampton Creek, arguing that the company was misleading consumers because Just Mayo was not "exactly, precisely, only and simply mayonnaise".
Unilever isn't only slamming Just Mayo for what it calls confusing branding — advertisements have called the stuff mayo, and the product's logo resembles an egg — it also says the company has no proof behind its claims of beating Hellmann's in a taste test.
Consumers and advocates have criticised Unilever over its lawsuit, calling it a response to the fact that Hampton Creek and other small food start-ups are chipping away at the company's huge market share.
In December, Unilever withdrew its lawsuit "so that Hampton Creek can address its label directly with industry groups and appropriate regulatory authorities", Mike Faherty, vice president for foods at Unilever North America, said in a statement at the time.
The FDA has also said Hampton Creek's cholesterol-free claim on Just Mayo isn't legitimate because the spread contains too much fat ("more than 13 grams of total fat per 50 grams") to make such an assertion.
Hampton Creek has 15 days to respond to the FDA's recent warning letter.
